Background camera from same scene in BGE
I resolved my problem a different way, not with cameras in the same scene necessarily, but with a master camera in one scene and the active slave cameras in all the other scenes. Here was my other question where this was explained by the friendly Monster: How to get a camera to copy location of character from a different scene in BGE
P.S. I wasn't asking the same question twice, I thought the cameras needed to be in the same scene at first, but then I thought maybe they could still be in different scenes, so I asked the second question. ;)